In "Mother, any distance," the speaker anticipates with a mixture of excitement and anxiety his independence from his mother. The mother helps the son become independent, realizing that this independence is a necessary and important part of his growth. She helps him to "measure [the] windows, pelmets, doors" of his new home. The son then ascends the stairs all the way to the loft, and the poem finishes with the son anticipating the "endless sky." The "endless sky" represents the final stage of his independence from his mother, and the speaker anticipates that he will either "fall or fly."
The fact that the mother actively helps the son to achieve his independence is indicated by the "spool of tape." She holds onto one end of the tape while the son holds onto the other, and the spool unreels as the son becomes more and more independent. The mother in this way is always there for her son, without crowding him or hindering his efforts to become independent. This is, on the mother's part, an act of selfless, generous parental love.
In "Before You Were Mine," the speaker of the poem has a more negative relationship with her mother. This is because the mother has made it clear to her daughter that she misses the life she had before her daughter was born. The mother seems to have told the daughter that the "decade ahead of [her] loud, possessive / yell was the best one," meaning that the years before the daughter was born were the best years of the mother's life. The implication of course is that the daughter has ruined the mother's life. In place of the supportive parental love demonstrated by the mother in "Mother, any distance," the mother in "Before You Were Mine" has burdened her daughter with feelings of guilt and insecurity.